Parallel Computer Architecture

478

CHAPTER

7

Scalable Multiprocessors

(1) Initiate send

(2) Address translation

on P

src

(3) Local /remote check

(4) Send-ready request

(5) Remote check

for

posted receive

(assume success)

(6) Reply transaction

(7) Bulk data transfer

Source VA->DestVA

or ID

Source

Send

P

dest

,

local VA,

len

I

Send-rdy

req

Destination

Recv

P

src

,

local VA,

len

Data-xfer

req

Time

FIGURE

7,10

Synchronous message-passing protocol.

The

figure illustrates

the

three-way hand-

shake involved

in

realizing

a

synchronous send/receive pair

in

terms

of

primitive network transactions.

If

a

matching send

is

present,

the

receive generates

a

ready-to-receive transaction.

When